Very Large π-Conjugation Despite Strong Nonplanarity: A Path for Designing New Semiconducting Polymers.

When two π-conjugated fragments are connected by a bond between two sp2 carbon atoms, a torsion around this bond is expected to break the overall π-conjugation. We show that for specially selected monomers, the π-conjugation is insensitive to torsions around a C-C bond up to about 60°. We provide a number of examples for this very unexpected phenomenon and a simple explanation. We propose that this feature can be incorporated into conjugated polymers to generate semiconducting materials that are extremely insensitive to structural disorder.